System of motor control.



No. 819,816. PATENTED MAY 8, 1906.

H. STUART.

SYSTEM OF MOTOR CONTROL. APPLICATION FILED JA1 I.20, 1904.

? INVENTOR ATTORNEY -tion.

UNITED STATES PATENT OFFICE;

. HARVE n. STUART, or WILKINSBURG,PENNSYLVANIA, Assienoa TO'wssrnvenousn ELECTRIC & MANUFACTURING COMPANY, A I CORPORATION OF(PENNSYLVANIA.

"SYSTEM F MOTOR CONTROL.

Specification of Letters Patent.

Patented ma a; 1906;

Application filed January 26, 1904. Serial No. 189,887-

,To all whom it may concern.-

Wilkinsburg, in the county of Allegheny and State of Pennsylvania, haveinvented a new and useful Improvement in Systems of Motor Control, ofwhich the following is a specifica- My invention relates to systems ofmotor control; and it has for its object to 'rovide a system of controlfor motors whic operate air compressors, pumps, and similar apparatus inwhich it is desirable to have the mopanying drawing, the singlefigure ofwhich 18 adiagram of a system of motor control organize in accordancetherewith.

The armature and .series, field-magnet Winding of a compound-wound motor1,

' which operates a fluidump 1 or similar apparatus, are connecte to oneside of a supply-circuit through the blade 2 of a mam switch 3, arheostat-arrn 4, and more or less of a variable resistance 5 and to theother side of such circuit throu h the other blade 8 of the main switch3. T e shunt-windin. of the field-magnet of the motor is connecte at oneside to the supply-circuit through the blade 9 of a field-dischargeswitch 10 and a rheostat 11 and at the other side through the otherblade 13 of the switch 10. When'the switch 10 is o ened, a projection13. pertaining to the blade 13 is brought into engagement with acontact-piece 14, thus eflecting a discharge of the shunt-field 12through a resistance lfi.

The main rlKeostat 16 is operated and controlled by a small series motor17, the armature-shait 18 of whichis geared, by means of a Worm 19 and aworm-wheel 20, to the con tact-ar1n 4. The field-magnet leads F and F-'and the armaturedeads A-iand A of the motor are connected to the lineand to a relay pparatus 21, a pressureage relay 22, a liZi it-switch 23,and a push-mitten switch 24 i the manner shown and as will be more fullyset forth in a description of the various circuits. I

sponding switch 27.

' The pressuiegage relay 22 comprises suitable mechanism which indicatesthe fluidpressure in a storage-reservoir l and automatically. opens orcloses the proper relaycircuits when the pressure exceeds or falls belowcertain predetermined limits. It comprises a pressure-actuated pointer24, which indicates the pressure on a scale 25 and which actuates-theone or the other of the switches 27 and 26, according as the pressure isat its up er or lower limit. It is of course understoo that thispressure-gage relay may be 0 'erated 'bymeans of any kind of pressure tat the o eration of the motor 1 will produce-t. e., t e apparatus whichmay be operated by the main motor 1 may be-of almost any desireddescription.

The relay a paratus 21 is employed for the purpose 0 selecting theproper circuits through the motor 17 when the pressure reaches the lowerlimit and the motor is to be started or when it has reached the u erlimit and the motor is to be stopped. s

relay comprisestwo switch-levers 28 and 29,

adapted to make contact with the roper stationary contact terminals ande ectromagnets 30 for operating the said levers. One of the magnets30'is rovid-ed witha winding 31 and the. other wit a winding 32, whichare respectively energized by the closing of the pressure-gage-relayswitch 26 and the corre- One of the magnets is also provided with aWinding 33 and the other with a corresponding winding'34, the

one or the other of which is closed when the circuits'of theoperating-motor 17 are closed, the latter two windings being severallyarranged vfor connection in series with the opcrating-motor circuit inorder to insure tne retention of the corresponding switch-lever inclosed position regardless of the fluctuations of thepressure-gage-relay pointer24.

The limit-switch 23 is adapted to 0 en and close the properrelay-circuits when t e rheostat-arm 4 has reached the limits of itsmovement, for which purpose any suitable device may be employed. Thatwhich I have indicated comprises a lug on the gear 20, which engages atthe limits of the movement of The rheosta t-arm 4 with the movableternii ial-block 3 7-, and thereby moves it intocon- 26 of the ressure a'e relav 2-2. msh-button switch 24, relay-magnet coil 31, contact 37 ofthe limit-switch 23 to the line by way of the blade 8 of the main switchThe energizing or the magnet-coil 31 0 )crates the switchlever 28, andthe circuit t irough the operating-motor 17 is from the line through themain-switch blade 2, the field-magnet wind ing from F+ to l relay-switchiever 28, contact-terminal 40', magnet-coil 33, the armature from A+ toA- the insulated end 41 of the switch-lever 23, contact 37 of thelimitswitch 23, to the line through the main-switch blade 8. A variableresistance is rovicled in a shunt to the main circuit throng i theoperating-motor 17 for the purpose of varying the current delivered tothe motor, connection to the circuit being made at the point 44 and atswitch-lever 23 by the contactpoint 45.

The motor 17 causes the switcharm 4 to move over the] contacts 42 and tothus cut resistance out of the circuit of the main motor, whichgradually speeds up as a result. W hen the switch-arm has moved to thelost contact-terminal 46, the movable terminal 36 of the limit-switch 23is thrown to make contact with the terminal 38, thus interrupting thecircuits through the relay-magnet coils 31 and 33, releasing theswitch-lever 2S and interrupting the circuit of the operating-motor 17,which. chines to a stop.

The main motor 1 now runs at full speed until the pressure in thereservoir l rises to the upper limit and causes the switch 27 of thepressure-gage relay 22 to close the circuit from the line through themain-switch blade 2, the conductor 39, switch 27, relay-magnet coil 32,contact-terminal 38, and movable terminal 36 of the limit-switch 23, tothe line through the main-switch blade 8. Opera tion of the relay-switchlever 29 then ensues,

and the circuit is closed from the line through i the main-switch blade2, the field-magnet winding oi the o crating-motor 17 from F to F- one"end 0 switch-lever 29, magnet-coil 34, the o crating-motor armaturefrom A to A t 1e insulated end 47 of the switch-lever 29, and thelimit-switch 23 to the line. The direction of thecurrent has now beenreversed through the armature or the operating;

stems switch may e closed, thus completin the h relay-circuit throughthe coil 32 in practically the same manner as isdone nutonnrtically bymeans of the pressure-gage relay.

It is conceivable that substantially the results herein set forth may besecured in sub stan-tially the same way Without employing the samecombinations of apparatus or the samearrsmgement of circuits, and Itherefore desirev it to be understood that my invention should beaccorded sufiicient scope to cover and include such variations "fro n1what is specifically shown and described.

l.- The combination with a main motor for o )erating pressure-producingapparatus, r ieostat for varying the current delivered to said motorhaving an arm, movable over contact-terminals, and a reversibleoperating motor for said rheostetmnn, of means for uu- V tomaticallyreversing the operating-motor when the pressure generated by said aratus respectively falls below and ises above predetermined limits, thatcomprises a main relay and o pressrue-switch which. is adapted to selectand close the proper circuit the through and a manually-operated switch101 bringing the main motor to rest.

2. The combination with a main motor for 0 erating pressure-producingapparatus, 21. rheostat for varying the current pessi through said motorhaving an arm movahie over contactterminols, and an operatingmotor forsaid rheostat-arm, of a main reds-y for determining the direction ofrotation of the operatingmiotor comprising switchdevers actuated byelectromagnets each having it pick-up winding, and 111851213 forautomatically energizing said winding that comprises a switch which isin communicationwith pressure-suprflied apparatus, and a.retainingwinding which is energized when the correspending s\\"itchleveris operated.

3. The combination with a main motor for operating pressure-producingumxnutus, e rheostat for varying the current pass ng through said motorhaving an ul'n'i movable over contact-terminals, and an operatingmotorfor said rheostat-arm, of a main relay for determining the direction ofthe flow cl energy in the armature of the op iting-inotor comprisingswitch-levers actuated-by electromagnets each having a pick-up Windingand a retaining-winding, and a second relay which is'in communicationwith pressuresupplied apparatus and which is adapted to automaticallyclose the circuits through one of said pick-up windings according as thepressure generated exceeds or falls below predetermined limits.

4. A system of motor control comprising a motor for operatingpressure-producing apparatus, a r. eostat for varying the currentdelivered to said motor'and having an arm movable over contactterminals,an operating-motor for said rheostat-arm, a limit switch which isactuated by said rheostatarm, a plurality'of circuits for theoperatingmotor, a relay for completing the proper circuit therethrough,a'pressure-switch 1n connection with said pressure-producin apparatusand adapted to automatically se ect the proper circuit through the mainrelay, and a manually-operated switch for bringing the main motor torest.

5. The combination with a main motor for 0 erating pressure producingapparatus, a r eostat for varying the current delivered to said motor,and a reversible operating-motor for said rheostat of a relay-switch forreversing the circuits of the operating-motor and a pressure-gage switchfor changing the circuits of'the relay-switch that may occupy either oftwo predetermined positions and is dependent upon the fluid-pressureproduced by the apparatus, its position being changed when said pressurefalls below or rises above predetermlned limits.

In testimony whereof I have hereunto subscribed my name this 12th day ofJanuary,

HARVE R. STUART. Witnesses: I

J 0s. VJ. ALEXANDER, BIRNEY HINES.

